Question

I’m having two weird errors

New error is when i tell java to draw a string that displays the coordinateness of x and y, It doesn’t.

public void paint (Graphics g)
{
    super.paint (g);

   //System.out.println ("Boolean: " + this.closeDoors);


    g.drawString("("+x+","+y+")",x,y);
}

Link to my program if you to compile it.
http://hotfile.com/dl/107032853/c81d927/Pigment.java.html

This is my complete program

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.awt.Graphics;

/**
 *
 * @author George Beazer
 */
public class Pigment extends JApplet 
{
    boolean closeDoors;
    private int x = 0;
    private int y = 0;


    public static void main(String [] args)
    {
            Pigment stuff = new Pigment();
    }
    public Pigment()

    {

        setBackground (Color.blue);
    }

    @Override
    public void init()
    {
         setLayout(new FlowLayout());
         addMouseListener(new MyMouseListener());
    }
    @Override
    public void paint (Graphics g)
    {
        super.paint (g);

       //System.out.println ("Boolean: " + this.closeDoors);


        g.drawString("("+x+","+y+")",x,y);
         if (x > 35)

            {
                            g.drawLine (35, 50, 570, 50);
                g.drawLine (35, 50, 250, 0);
                g.drawLine (250, 0, 570, 50);
                g.drawRect (50, 50, 500, 350);
                g.fillRect (100, 75, 80, 80);
                g.fillRect (400, 75, 80, 80);
                g.fillRect (240, 200, 125, 200);


            }

        else
            {        
            g.drawLine (35, 50, 570, 50);
            g.drawLine (35, 50, 250, 0);
            g.drawLine (250, 0, 570, 50);
            g.drawLine (180, 120, 100, 120);
            g.drawLine (400, 120, 480, 120);
            g.drawLine (140, 75, 140, 160);
            g.drawLine (450, 75, 450, 160);
            g.drawRect (50, 50, 500, 350);
            g.drawRect (100, 75, 80, 80);
            g.drawRect (400, 75, 80, 80);
            g.drawRect (240, 200, 125, 200);
            g.drawOval (330,280, 20, 20);
            }


    }
    private class MyMouseListener implements MouseListener
    {
        public void mouseClicked (MouseEvent e)
        {
            x = e.getX();
            y = e.getY();

        }

        public void mouseEntered (MouseEvent e)
        {


        }
        public void mouseExited(MouseEvent e){}
        public void mousePressed (MouseEvent e){

        }
        public void mouseReleased (MouseEvent e){}

    }

}

Answer 1

With regards to your first question, the reason that you’re getting a compiler error here:

if (x > 35)
{
    g.drawLine (35, 50, 570, 50);
    g.drawLine (35, 50, 250, 0);

    repaint();
    break;  
}

Is that this break statement is not actually in a loop. In Java, you can break out of while, for, do...while, and switch statements, but not if statements. There’s not a particularly good reason for this – it’s mainly historical – but the compiler does indeed enforce it.

Of the three aforementioned control structures, for, while, and do...while are referred to as loops because they execute code potentially many times. The break statement in this case is a way of saying “please abort execution of the current loop; I don’t want to run it any more.” Its opposite is continue, which means “please go to the next iteration of this loop.”

The reason you can break out of a switch is because Java’s switch statement is based on the C programming language’s version of switch in which labels are “fall-through.” In this context, break means “I have finished executing all of the code I want to execute in this particular label; please get me out of this statement.” Interestingly, you can break out of a switch, but you can’t continue.

However, you cannot break out of an if statement. There is no high-level reason for this, and in fact the language designers could just as easily have allowed this behavior to mean “stop executing this part of the if statement.” I think the reason they opted not to do this is that if statements have a sort of “implicit break” at the end of each handler. For example, if you write

if (condition()) {
    // A
} else {
    // B
}
// C

Then after executing A, the control flow will immediately jump you to C, rather than falling through to the else handler.

If you want to simulate a break out of of the middle of an if statement, you could do something like this:

if (condition()) {
     // code

     if (someOtherCondition()) {
          // more code
     }
}

The idea here is that you run the if statement for some time, then decide using a second if statement whether or not to run the rest of the code in the loop.

Hope this helps!